Electric regulator



w. E. M0035.

ELECTRIC REGULATOR.

APPLICAHON HLED Nov. 16, 1918.

1,378,971 n Patented May 24, 1921.

2 SHEETS-SHEET l.

W. E. MOORE.

'ELECTRIC REGULATOR.

APPLICAHON HLED N0v.16,1918.

1,378,97 l Patented May 24, 1921.

2 SHEETS-SHEET 2.

@mambo/b M//Y//am Maar-e C11@ ma UNITED STATES PATENT OFFICE.

ELECTRIC REGULATOR.

'Specification of Letters Patent.

Patented May 24, 1921.

Application led November 16, 1918. Serial vNo. 262,805. I

To all whoml t may concem:

Be it known that I, WiLLIAM E. Moons, a citizen of the United States, residing at Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Electric Regulators, of which the followmg 1s a specification.

My invention relates to improvements in electrical regulators, and 1t consists in the combinations, constructions and arrangements herein described and claimed.

An object of my invention is to provide a device which may be used in connection with prime movers, electric furnaces, electric' circuits, etc., for automatically controlling the same, and in which the instant starting or stopping of the controlling or regulatmg motor may be effected without overrunning or hunting.

A further object of my invention is to provide an electric regulator which is relatively simple in-construction, and which is provided with auxiliary manual controlling means which may be worked in conjunction with the automatic control without interference.

A further object of my invention is to provide an automatic regulating .device for regulating the length of the arc 1n an electr1c furnace.

Other objects and advantages will api pear in the following specification, and the novel features of the'invention will be particularly pointed out in the appended claims.

My invention is illustrated in the accompanying drawings, -forming part of this application, in which- Figure 1 is a diagrammatic view showing one embodiment of my invention; and

Fig. 2 is a similar view showing a modied form.

In Fig. 1, I have shown, diagrammatically, an arrangement by means of which the flow of water to a water wheel in an electric generating plant mav be governed.I

In the drawings, I indicate a iiy-ball governor of the ordinary kind, which may be connected with the water wheel (not shown). This, governor actuates a walking beam or lever 2, which is pivoted at 3, and which is provided with a contact 4 arranged to engage upper and lower contacts 5 and 6 respectively, depending upon the Speed ofthe water Wheel, and the posidevice of this kin tlon of the ball governor. The closure of the contacts 4 and 5 is designed to energize a magnet 7, while the closure of the contacts 4 and 6 is designed to energize a mag- `net 8 in the manner hereinafter explained.

The vmagnet 7 controls a single pole double throw swltch S, the arms of which bear contacts 9 and l0 respectively, the former arranged to engage a stationary contact 11, and the latter adaptedto `engage a stationary contact 12. One arm of the switch S is provided with a spring 13 which keeps the contacts 10 and 12 closed when the magnet 7 1s denerglzed. y The energization of the magnet 7,J however, causes the closing of the contacts 9 and 11 and the opening of the contacts 10 and 12.

. The magnet 8 controls a switch S which is similar to the switch S, the parts 9 to 13 mcluslve corresponding to the parts 9 to 13. A control or winding motor 14 which would be connected on to the means for regulating the source of water supply, as v for instance the gate of a turbine water Wheel, may be provided with any suitable mechanism for operating the gate, this mechanlsm being shown diagrammatically at 15 and 16.

In a direct current power plant, the water wheel would, of course, be connected with a direct current generator, and the latter might be used as the source of current for actuating the control or winding motor 14, but I prefer to use a'separate motor-generator set, since the latter is always available, even in case the main power generator should, for any reason, be put' out of commission. The motor generator set consists of a direct current generator 17 driven by a motor 18, which may be a direct current motor, or of the ordinary induction polyphase motor type, or any other type of motor. On the shaft connecting the motor to the generator there'is preferably placed ay `When utilizin an automatic regulating there is a possibility of overrunrning or hunting, that is to say, the winding,q motor may operate the winding mechanism too far in one onrection before .the automatic speed governor can 1function to stop the motion. ln order to allow rapid motions ot the winding gear, it is, therefore, very desirable to provide anti-huntin means, This may be accomplished by applying a reactive force to the speed governor, tending to open circuit after the same has been established. To accomplish this purpose, there are incorporated in this regulator two solenoids 4:2 acting on the solenoid cores attached to an extension 2X of the walking beam 2. are connected across the armature of tbe winding motor le, in such i ner as to receive an impulse proporti ai to the speed thereof, as hereinafter set l The operation of the apparatus thus far described as follows: is *lining that the speed oi"- the prime mover or water wheel is decreasing, it is obvious that ball governor i, lowering, would cause the wailting 2' to move so as to eventualiy close the contacts and 5. This energizes the magnet 7, the energizing' circuit beingn from the generator l?, through the switch arm 2l, conductors 22, 23, 24e, walking beam 2, contacts l 5, conductor v29, magnet 7, conductor 30, 3i, switch arm 32, and by 33 to generator. The mamaet i, being energized, closes the conta cts Q ll, and opens the contacts lG-l or the vswitch S, T his completes a circuit through the motor le, from the generator l? through switch arm 2l, 22, resistors Se? 31th, contacts ll. and 9, conductor 35, motor le, 36, contacts l() and l2, resistor 3%, conductor 3l, 32 and 33 to generator. in tiie 1,ore-sent instance, the motor la is shown as being; provided with a shunt eld 38, the energizing circuit oi this field being from the generator 17 switch arm 2l, 22, 23, coil 38, conductor 39 to conductor 3l and baclr to .the generator by the path already traced. -The operation ot' the motor 14E regulates the gates and causes an increase (in the present example) in the power supply, thus speeding up the prime mover.

When the governor l has been increased in speed to the point where its y-balls will rise and break the contacts 4 and 5, then the magnet 7 is denergized, the spring; i3 causes the reverse movement of the switch S,- closing the contacts 10 and l2, and opening the contacts 9 and ll. The effect oli* this is to short circuit the armature of the motor through the resistors 37a and 37', thus applymg a dynamic brake to bring the winding mechanism to an instantstop, tending to reduce overrunning or hunting.

elle

To insure the prompt stopping of the winding motor le, however, E provide the solenoid e3, which is connected across tbe Tbese solenoids v neraari armature ,of the motor as shown in the drawing, and which receives an impulse proportional to the speed ot the motor over the following path: from the motor la, through conductor 35, conductor 35", solenoid 43, conductor 45, contacts 12p-l0, and by couductor 36 to motor. The solenoid modifies the action of tbe governor l, e'. e., it tends to break the circuit at the contacts 4--5 loe-- fore it would ordinarily'be broken by the governor, were the solenoid not present. llhe force exerted by the solenoid is not sutiicientof itselovercome the action or the governor, but it is designed so that it wiil act tbe time desired to prevent the motor from overrunning.7V

Should the speed of the prime mover continue to increase to tlielpoint wheretbe gow. ernor i would the contact into eugagement with the contact 6, then the magnet 8 would be energized, the energizing circuit be to the contact 4; over the path already traced in connection wien the magnet thence through contact 6, conductor 40, 8, and bacir to the generator over tbe p Lurevicusijytraced- The enerM gization of? tne magnet 8 causes the closing or the contacts Q and il, and the opening ot the contacts i6 l2. Current now iiows from generator through 2l, 22 Sea, ll, 9, switch S', 36, mot r le, 35, switch S, l0, l2, 37b, 3l, 32, 33 back' to generator, re"ersirig the direction of rotation ci" the motor causing the winding mechanism to close the gates tocut down the power ilow. l

As prime mover slows up, due to tbe decrease of power iiow, tbe contacts l and 6 arebroiten, the switch S is retracted by the springl to its normal position, and the armature ci the motor is again short circuited through the resistors 37a and 37b, again applying the dynamic breite so as to bring the winding mechanism to an instantaneous stop. This action is made certain by the solenoid a2 which operates in the same manner as described in connection with solenoid 4&3.,

lin Fig. 2, l have shown an arrangement by means or' which the vlength of the arc in an electric furnace mayl be automatically regulated, as well as means for accomA plishing such regulation manually, if desired., l'n this ligure the electric furnace is shown diagrammatically at 46, the electrode fl? being raised or lowered by means. of the winding motor le through mech# anism 4&8 including thecable 49.. It will'- that actually shown might be used without departing from the spirit of the invention. The electrode e7 is red by a circuit running through a. vcurrent transormer 50 to the power transformer 51, or other suitable source of supply. The current transformer 50 energizes a solenoid 52 which, throughits plunger 53, operates the walking beam 2, the weight ofthe plunger being partially balanced by means of av spring 54. The arrangement is such that when the solenoid 52 is energized, the plunger 53 moves upwardly, thus tending to lower the .opposite end of the walking beam. When the solenoid is denergized the contacts 4 and 5 are closed, being biased to this position by the weight of the plunger 53. When the furnace conditions are normal, the lsolenoid 52, assisted by the spring 54, equalizes the force due to the Weight ofthe plunger 53 in such a way as to open both contacts 4--5 and 46. In order to adjust the apparatus for a variation in the current through the elec-v trode circuit, a dial rheostat 55 is shown, connected in parallel with the wires 56 and 57, in such a manner as to shunt a portion of the current developed in the transformer 50 through the rheostat, thus sending only a portion of the current to the solenoid 52. The rheostat 55 is located in convenient range of the machine being regulated, which, in the present instance, is the electrode in the electric furnace, so that the operator may vary the current and therefore the flow` ofpower, as desired.

In order to provide for manual regulation,

I may use a drum switch. In Fig. 2 I have shown this drum switch as a diagrammatic development. Thus the surface of the drum may be provided with contacts 58, 59, 60, 58- 59 and 60 which are relatively short, while the contacts 61, 61', 62, and 63 are longer. A series of contact buttons 64 to 68-inclusive, and 64 to 68 inclusive, are provided.

on a stationar frame. (Notshown.) The lines -w indicate the different positions of the drum and its contacts with respect to the stationar contacts. tion of the rum is that shown in Fig. 2. In this position a conductor 69, .which connects the contacts 58 'and 58', forms part of the automatic regulating circuit.

It will'be observed that there is an automatic no voltage rela or circuit breaker 70, which is controllew by the transformer 51, and which, as long as the ltransformer is active, completes a circuit from the conductor 23, whichy leads from the generator 17 to the contact 64, by means of the wire 71.

Let us assume that the current iow decreases below normal, as, for instance, when the electrode 47 burns away and the arc becomes too long. Then the walking beam 2, owing to the reduced pull of the solenoid, may'close the contacts 4 and 5, thus energizing the magnet 7, the energizing circuit being as follows: from the generator 17, through 21, 22, 23, 72, 70, 71, 64', 58', 69, 64, 58, 24, 2, 4, 5, 29, magnet 7, 30, 41,y 31,

' trol ineffective.

The normal posi- 32, 33 to generator. The actuation of the magnet 7 closes the contacts 9-11 and opens contacts 10--12, thus energizing the Winding motor 14 over the circuit already traced in connection with Fig. 1. This tends to lower the electrode 47 and to shorten the arc to normal.

' When the ycurrent increases in the electrode circuit the solenoid 52 may cause the closure of the contacts 4 and 6, and in such event the magnet 8 is energized, and the switch S is operated to effect the reversal of the direction of rotation of the winding motor 14, thus raising the electrodes. These operations are repeated to adjust the resistance of the electrode circuit to such a point aswillmaintain the current in the electrode circuit at the desirable limit for which the apparatus is adjusted. In this case, as in.

the case of .the walking beam shown in Fig. 1, the solenoids 42 and 43 are connected across the terminals of the Winding motor 14 in order to prevent hunting or overrunning.

Referring now to the manual means of control, it will be noted that there are seven positions. The central position is the automatic, or the position in which the drum .In either case the contacts 58 and 58 will move so as to break the circuit, thus rendering both the automatic and the manual con- If it should be desired to lower the electrode, the drum switch is moved to the right in Fig. 2. Let us assume that it is moved to the position marked hand 1. The following contacts are engaged: 61 with 65, 62 with 67 and 63 with 68 Current now energizes the magnet 7 over the following path, from the generator 17, through 21, 22, v23, 75, 67', 62, 59, 61, 65,

of the contacts 9 and 11 ator. The closing 76, 29, magnet 7, 30, 41, 31, 32, 33, to generforms an energizmg circuit for the winding j motor 14, from the enerator 17, through 21, 22, resistors 34a an 34b in series, 11, 9, 35, motor 14, 36, 10, 12, resistor 37, 31, 32, 33, to generator. It will be noted that the re slstors 34, 34", and 37a are in series, and

the motor 14 therefore operates at fractional speed.

When the drum is moved further to the right to the position marked hand 2, the energizing circuit of the magnet 7 is maintained, but the contact 59 of the drum-switch now engages 66, and the contact 60 engages 68. The actuating circuit of the motor14 is now from generator 17 through 21, 22,23, 75, 67', 62, 59, 66,77, 34h, 11, 9, 35, motor 14, 36, 10, 12, to 78. From this point two circuits are established,-one through theresistor 37iz and by 3i, 32 and 33 to generator, and the other through 79, 80, 68', 63', 8l, 60,

68, 82, resistor 37b, 3l, 32, 33 to generator,

Furthermore, a ortion of the current tending to energize t e motor le, when the' drum switch is in the position marked hand 2;"

would 20W through the resistor 34a in par- -allei with the circuit through the drum and correspondingly increases its speedE g vWhen the drum switch is returned to the ofi position, the magnet 7 is denergized, and the switch S returns to its normal position, thereby short circuiting the motor i@ and applying a dynamic brake in the manner already described,

When the drum switch is moved to iett, 'or raise direction, the magnet' 3 is energized, operating the switch and esnl tabiishing similar circuits ,to those already traced. With certain types of winding mechanism it is necessary to either operate the mechanism at diiierent speeds in the two diliierent directions, or Where the regnlanr resistance to movement is greater in one direction than it is in the other, it is necesi sary, in order to obtain the saine speed in 1. this point the circuit divides,

the opposite direction, to provide diiierent amounts oi resistancein the motor circuit in thediierent directions, in the foregoing description, and from the drawing, it wiii ce noted athat when the switch S is diosed, both sections of the resistances 342g 34th are in series with the motor it, while when the switch Sp is closed, only the section 3f@ is insertedo The energizing circuit of the motor ld has been traced in connection with the position hand 2 at the right, iVhen the drum switch is at 6hand 2 at the ieit, the energia=I ing circuit of the motor is as ioliows: Jtrom generator i7, through 21,' 22, to wire 23. rlit a part going through resistor 3ia to Wire 7, and a part going through 23, 7 5, 37, 3d, t7, 32, 59", 66', 85, 3th to wire 77, thence through contacts n and ef, 3c, motor ii, e5, io ein is; At this point the circuit divides, part going through resistor 37", 3i, 32, 33 to generator,

and the other through 82, 68, 63, 3i, 60'?, 63;,

78, resistor 372, 3i, 32, 33 to generator., Resistors 37a and 37 b will, therefore, hein parallei.,

A still further increase in speed on position hand 2 to the hath-may be obtained b connecting contact 66 to contact .77, and e iminating conductor 85, thus eliminating any ortion of resistor 3ft from the circuit on t is positionB The connection of the wires 77 and 3i to the respective resistors,

may be adjusted so that the relative amount I astanti of resistance in each arm or branch may be regulated to provide for varying speeds of the motor, as desi-red,I l

The solenoids d3v and 42 operate in substantially the same manner as the soienoids 4t2 and d3, already described in connection with Fig., i. When the solenoid 52 actuates the walking heam 2 to ciose the contacts i and 3, the magnet 8 is actuated, and the switch S is moved so as to com lete the circuit to the motor it, as already escribed. The soienoid 4:2 is energized proportitniaiijyto the counter electro-motive force dencioped in the armature of the motor le, by wire 36, 88, solenoid i2", 33, 32, i2, i0, and 35, back to the motoro The solenoid 2f tends to oppose the soienoid 52, and thus tends tol open the contacts i and 3 more promptly than wouid be the case if such action were absoiiteiy dependent upon the decreasing currentl in the .solenoid 52, due tc the readjustment the electrode positicuir The reactive torce, iiowevenis suiiicient to open the contacts sli-3, or iss-5, eniy when smaiier changes are indicated by pinnger.` The soienoid 52 is not, in itseiii, snif cient to open these contacts where larger changes of power are by the indiu eating mechanism. in other words, the reactive or anti-hunting device is so proportioned that it would not interrupt or sion' down the speed of the winding metorwhen overrunmng iff the power supply to the transformer lyshould fail from any cause, the circuit breaker 70 would operate to break the circuit through the re later, thus obviating the danger of a sud en rush of heavy current through the electrode when restarting the furnace, which might be immediateiy submerged in the bath by the reguiating device, were not the latter put out of commission by the circuitbreaker A regulator constructed and arranged as described above has the advantage otgreat simplicity, instant startin of the winding motor, and instant stopping, A diculty often experienced in reguiators is their tend;- ency to hunt or overrun, and this danger is entirely obviated by my improved apparatus, thus permitting more rapid adjustments to be made by the reguiator, The faciiity izo noteert with which the mechanism is governed, either automatically or by hand, is another feature of importance. The provision of means by which the motor may be controlled so as to operate in either direction at fractional or part speed, renders the device particularly desirable in those cases where, as -already pointed out, it is advantageous to operate at one speed in onedirection and at a diderent speed in the opposite direction.

it is obvious that a governor responsive to variations of velocity, voltage, pressure, quantity, or other variable, as well as power, might be used, and also that the regulator might be employed for other purposes than those disclosed herein, without departing in the least from the spirit and the scope of the invention.

I claim:

l. A regulator, comprising a governor having a movable element, a source of current, a motor, means controlled by the governor for connecting the motor with the source of current, and electro-magnetic means comprising two independent oppositely acting portions connected with said motor for exerting a reactive force -on said governor element. v

2. A regulator, comprising a governor having a movable element, a source of current, 'a motor, means controlled by the governor for connecting the motor with the source of current, and electro-magnetic means comprising two independentJ oppositely acting portions connected with said motor for exerting a reactive Jforce on said governor element, lsaid reactive force being substantially proportional to the counter electro-motive force of the motor.

3. A regulator, comprising a governor having a movable element, a source of current, a motor, means controlled by the governor for connecting said motor to and disconnecting it from said source of current,

and means for preventing the-overrunning or hunting of the motor including two separate electro-magnetic means connected with said motor, and disposed to urge the movable element in opposite directions, forA exerting a reactive force onsaid governor element.

4:. An electric regulator, comprisin g a governor, a source of current, a motor, auxiliary means controlled by said governor for connecting or disconnecting said motor from said source of current, and manual Ameans comprising aswitch operative in one position to throw the governor into circuit with the auxiliary means, whereby automatic control is secured, and operative in other positions to provide independent manual control of said auxiliary means.

5. An electric regulatgr, comprising a governor, a. source of current, a motor, a pair of magnets controlled by said governor, a

ing or disconnecting said motor, and manual' means comprising a switch operative in one position to throw the governor into circuit with the magnets, whereby automatic control is secured, and operative in other positions to provide independent manual control of said magnets. 1

6. An electric regulator, comprising a governor, a source of current, a motor, circuit connections between said source oi current and said motor, said circuit connections including resistors, a pair of magnets controlled by said governor, a switch actuated by each magnet and arranged to form part of the motor circuit, and a manual controlling switch for controlling said magnets independently of the governor, said switch in one position being operative to throw the governor into circuit whereas in other positions it is operative to directly manually .control the magnets and to disconnect the governor from the circuit.

7. An electric regulator, comprising a governor, a source of current, ia motor, circuit connections between said source of current and said motor, said circuit connections including resistors, auxiliary means controlled by said governor for controlling the said circuit connections, a manually operated switch having a plurality of contacts for independently controlling sai'd auxiliary means and for determining the amount of resistance brought into the motor circuit.

8. An electric regulator, comprising a governor, a source of current, a motor, means actuated by said governor for connecting said source of current with said motor, resistors in said motor circuit, and manual means for determining the amount of resistance brought into the motor circuit, .whereby the speed of the motor may be varied. p

9. An electric regulator, comprising'a governor, a source of current, 'a motor, mea-ns actuated by the governor for connecting and vdisconnecting said motor from said source 'of current, and Vmanual means for controlling said last named means independently of 'the governor, said manual means being movable to different positions to vary' the direction of rotation or the speed of the motor.

10. ln an electricregulator, a governor, a source ocurrent, a motor, means actuated by said governor for connecting and disconnecting said motor from said source of current, an auxiliary electro-magnetic device for aiding the movement of the governor in one direction, and a second electro-magnetic device for aiding the movement of the governor in the opposite direction, and circuits connecting the'said auxiliary electromagnetic devices to the motor circuits whereby said' devices are actuatedv in response to l the direction and value of the counter electromotive force of the motor.

l1. In an electric regulator, a governor, a source of current, a motor, means actuated by said governor for connecting and disconnecting said motor from said source of current, an auxiliary electro-magnetic device for aiding the movement of the governor in one direction, and a second electro-magnetic device for aiding the movement of the governor in the opposite'direction, said electromagnetic devices being selectively connected with said motor and operating with aforce substantially proportional to the speed or counter electro-motive force of the motor.

l2. 'in an electric regulator, a governor, a source of electricity, a motor, a switch actuated by said governor, a pair of electromagnetic devices controlled by said switch, and two single-pole double-throw switches, each operated by a corresponding one of said electromagnetic devices, said' motor being lnormally short-circuited through both oi said single-pole double-throw switches, an electromagnetic means cooperating with said governor to actuate it in response to variations of electrical condition of said means, and reactive means' adapted to be electrically connected in circuit with said source of electricity and said motor by the said singlepole double-throw switches to exert a force on the governor which is a function of the counter electromotive force o'fsaid motor.

13. lin an electric regulator, a governor, a source of electricity, a motor, a switch actuated by said governor, a Tpair of electromagnetic devices controlled by said switch, and two sitgle-pole double-throw switches, each o era by a correspondin one of said e ectromagnetic devices, sai motor being normally shom-circuited through both of said single-pole double-throw switches, an electromagnetic means coperating with said governor to actuate it in response to variations of electrical condition of said means, and reactive means adapted to be electrically connected in circuit with said source of electricity and said motor by the said `singlepole double-throw switches to exert a force on the governor which is a function of the counter electromotive. force of said lmotor,

the said torce being alwa s so directed as -to oppose the existing ten ency of the govsaid single-pole double-throw switches, the,

operation ofueither one of the last named switches serving to remove the short-circuit,

one serving to complete the circuit from the Source of electricity through the motor in one direction, and the operation of the other switch servingv to reverse the circuit through one element of the motor, an electromagnetic means 'cooperating with said governor to actuate it in response to variations of electrical condition of said means, and reactive means adapted to be electrically connected in circuit with said source of electricit and said motor by the said single-pole ouble-throw switches to exert a force on the governor which is a function of the counter electromotive force of said motor.

l5. in an electric regulator, a governor, a source of electricity, a rio-voltage relay cooperating with said source of electricit to open the circuit when the current fails, a motor, a switch actuated by said governor, a pair of electromagnetic devices controlled by said switch, and two'single-pole doublethrow switches, each operated by a corresponding one of said electromagnetic devices, sald motorlbeing normally short-circuited through both of said single-pole double-throw switches, an electromagnetic means coperating with said governor to actuate it in response to variations of electrical condition Aof said means, and reactive means adapted ,to be electrically connected in cirmotor bythe said single-pole double-throw switches to exert a force on the 4governor which is a function of the counter electromotive force of said motor.

16. An electric, regulator comprising a governor, a source of current, a` motor, means controlled by said governor for connecting said motor to or disconnecting it :tromjsaid source oi current so as to start, stop and reverse the same, and a manual drum switch for controlling said motor independently of the governor, said switch in one position serving to vest the control of the motorA in vsaid governor,l and in other positions serving to de rive the governor of such control and itse f manually control the motor directly.

17. In 4an electric regulator, agovernor, a source of current, a motor, a switch actuated by said governor, a air of electro-magnetic devices controlled y saidvswitcli, and manual means for independently controlling said devices, said last named means compris' ing a drum swltch, and contacts carried by said drum switch, certain of said contactsv cuit with said source of electricity and said leading to the first named switch, and others leading to the circuits of the electromagnetic devices directly, whereby the drum switch in Aone osition throws the governor into circuit, w creas in' other positions the governor'is disconnected from the circuit, and the electroma `etic devices are controlled manually o y.`

governor for connecting the motor with the generator, electro-magnetic means connected with said motor for exerting a reactive force on said governor, and a hand operated switch serving in one position to connect the governor into the control circuit, and inother positions disconnecting the governor from said circuit and itself servlng as a manual control device for independently actuating said switch operating means.

19. A regulator, comprising a governor, having a movable switch arm, a source of current a motor, means actuated by the governor for connecting the motor with the source of current, a pair of opposed solenoids coperating with the switch arm, and connections between the solenoids, and the Amotor whereby the solenoids are actuated.

20. Apparatus forregulating electric arc furnaces comprising an electrode to be shifted, a power circuit through said electrode, an electric motor operatively connected to said electrode,a pair of switches for starting, stopping and reversing said motor, a governor responsive to varlations of energy in the electrode circuit for controlling said switches, and two separate means, each comprising a circuit including respectively one of said switches, for automatically modifying the effective action of said governor after the same has responded to a variation of energy, whereby hunting is reduced. i

l 21. Apparatus for regulating electric arc furnaces comprising an electrode to be shifted, a power circuit through said electrode, an electric motor operatively connected to said electrode, a pair of switches for starting, stopping, and reversing said motor, an electromagnetic governor responsive to variations of energy in the electrode lcircuit for controlling said switches, and

two separate means, each including respectively one of -said switches, for automatically decreasing the effective force actuating said electromagnetic governor after the same has responded to a variation of energy. 22. Apparatus for regulating electric arc furnaces comprising an electrode to be shifteda power circuit through said electrode, an electric motor operatively connectedwith said electrode, a pair of singlepole double-throw switches for starting, stopping, and reversing said motor, the arrangement being such that either of said switches when thrown in one direction starts the motor, and when thrown in the other. direction stops the motor, lthe motor armature being normally connected in a circuit closed on itself through both of said 

